CN111173916B

CN111173916B - Cooling priority valve for a hydraulic system of a motor vehicle transmission

Info

Publication number: CN111173916B
Application number: CN201910998094.9A
Authority: CN
Inventors: A·哈伯施托克; A·豪格; T·施密特; M·赫尔曼
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 2018-11-09
Filing date: 2019-10-17
Publication date: 2024-04-19
Anticipated expiration: 2039-10-17
Also published as: DE102018219122A1; US20200149562A1; US11022157B2; CN111173916A

Abstract

The invention relates to a cooling priority valve (5) for a hydraulic system (4) of a motor vehicle transmission (3). The cooling priority valve comprises a valve housing (6), a valve core (7), an inlet (18), an outlet (15) and a further outlet (21). A secondary system pressure circuit (39) of the hydraulic system (4) can be connected to the inlet (18). Furthermore, a cooler (54) can be connected to the outlet (15) or to the further outlet (21), and a suction plenum section (44) can be connected to the outlet (15) or to the further outlet (21). The cooling priority valve is configured for moving the valve spool within the valve housing into an initial position in which the inlet is connected to neither the outlet nor the further outlet (21), a first control position in which the inlet is connected to the outlet, and a second control position in which the inlet is connected to the outlet and the further outlet.

Description

Cooling priority valve for a hydraulic system of a motor vehicle transmission

Technical Field

The present invention relates to a cooling priority valve for a hydraulic system of a motor vehicle transmission. The invention further relates to a hydraulic system having a cooling priority valve, a motor vehicle transmission having a hydraulic system and a motor vehicle having a motor vehicle transmission.

Background

Hydraulic systems, in particular for automatic motor vehicle transmissions, are known, which comprise a pump system, a high-pressure circuit (main-system pressure circuit) and a low-pressure circuit (secondary-system pressure circuit) and a suction-charging section (Saugaufladung). The suction plenum section is understood to be the return portion that leads the volume flow that is oversupplied by the pump back to the suction side of the pump. The pump system can be designed, for example, as a two-stroke vane pump with a rotational speed-dependent delivery volume flow.

The secondary system pressure circuit may be divided into sections for cooling and lubricating the transmission and sections for cooling the starting elements. The secondary system pressure circuit uses a certain oil volume flow for cooling the integrated starting element, the oil quantity being controllable by means of a cooling valve. This may be done indirectly by controlling the amount of oil via a variable pressure of the cooling valve. The split ratio of the cooling oil flow may be determined by the ratio of the orifice provided upstream of the integrated startup element and the orifice provided upstream of the cooler.

In particular, the integrated starting element must be cooled down intensively during starting. The output speed of the transmission is very low, so that no high cooler flow (or lubrication) is required. The cooler flow (outside the split ratio) cannot be reduced without reducing the integrated starting element cooling. The secondary requirement affects the size (ccm/U) of the oil pump, as in the case of starting sufficient secondary oil must be provided to ensure the required cooling of the integrated starting element.

Disclosure of Invention

The object of the invention is therefore to improve the cooling of an integrated starting element.

The object is achieved by the solution of the independent claims. Advantageous embodiments are the solutions of the dependent claims, the following description and the figures.

According to the invention, the supply of cooling oil to the integrated starting element is improved by an additional flange on a system pressure valve of a secondary system pressure circuit of a hydraulic system of a motor vehicle transmission. The system pressure valve may be configured as a pressure relief valve. The system pressure valve is hereinafter referred to as a "cooling priority valve". The cooling priority valve helps to prevent the pump from being enlarged or the pump from being reduced in size. The consumption of the hydraulic system can also be reduced. No additional pressure regulator or additional valve is required here to control the chiller flow.

In this sense, according to a first aspect of the invention, a cooling priority valve for a hydraulic system of a motor vehicle transmission is provided. The cooling priority valve includes a valve housing, a spool, an inlet, one outlet, and another outlet.

A secondary system pressure circuit of the hydraulic system can be connected to the inlet. Pressurized oil from the secondary system pressure circuit may be supplied to the cooling priority valve. The secondary system pressure circuit may also be connected (e.g., via a cooling valve and an orifice) to the integrated startup element. Here, for example, the secondary system pressure circuit can be connected to the inlet-side port of the cooling valve. The orifice can be connected on one side to an outlet side port of the cooling valve and on the other side to an integrated starting element.

The cooler may be connected (in particular by means of an orifice which is connected on one side to the secondary system pressure circuit and on the other side to the cooler) to the outlet or to the further outlet. A suction plenum section connected to the suction side of the pump or to the pump system of the hydraulic system can also be connected to the outlet or to the further outlet. Thus, a cooler can be connected to the outlet and a suction plenum section can be connected to the further outlet, or a suction plenum section can be connected to the outlet and a cooler to the further outlet. The connection of the two outlets to the "cooler" and the "suction plenum section" can thus be exchanged, which simplifies the installation situation and can be achieved simply by changing the control times on the valve cartridge. The suction-charging section is connected here in particular to the suction side of a pump of the hydraulic system. The suction-charging section may comprise a line leading to an inlet of the pump or pump system, through which the pump or pump system can be additionally (in addition to the supply via the tank) supplied with oil.

The cooling priority valve is configured to move the valve spool within the valve housing into an initial position, a first control position, and a second control position.

In the initial position the inlet is connected neither to the outlet nor to the further outlet. The term "connected" is understood in particular to mean that the interconnected elements are connected in hydraulic conduction with each other, i.e. hydraulic fluid, in particular oil, can flow from one element to the other and vice versa if desired. The term "separate" or "not connected to each other" is understood in particular to mean that the mutually separate elements are connected to each other in a non-hydraulic connection, i.e. hydraulic fluid, in particular oil, cannot flow from one element to the other and vice versa if desired.

When the valve element is in the initial position, pressurized oil can enter the cooling priority valve, in particular into a valve chamber of the cooling priority valve, through the inlet. But the oil cannot leave the cooling priority valve through the outlet and the further outlet for supply to the cooler and/or the suction plenum section. The total oil volume flow (or at least a substantial portion thereof) of the secondary system pressure circuit can be used to cool the integrated startup element. For this purpose, a section of the secondary system pressure circuit can be led past the cooling priority valve to a cooling valve, which is connected to the integrated starting element for cooling it.

Instead, in a first control position the inlet is connected to the outlet. The pressurized oil from the secondary system pressure circuit can now leave the cooling priority valve through this outlet for supply to the cooler or the suction plenum section, depending on which of these two elements is connected to the outlet.

In the second control position, the inlet is connected not only to the outlet but also to the further outlet. Whereby pressurized oil from the secondary system pressure circuit can now leave the cooling priority valve through the outlet and the further outlet for supply to the cooler and the suction plenum section.

In a first embodiment, the valve housing has three valve flanges, each of which forms a valve chamber. The inlet, the outlet and the further outlet are each arranged on one of the valve flanges and are each connected to one of the valve chambers.

The valve flange can be hollow in the interior and in each case form a valve chamber. The valve chamber described in the present application may be a chamber within a valve housing. These chambers can be filled by a valve insert in the region of the valve housing axial bore. The valve chamber may extend further outward in the radial direction of the valve than the valve housing axial hole extending in the longitudinal direction of the valve. The axial bore is used here in particular for guiding the valve element together with its piston rod and piston in the valve housing. The valve chamber can form a pressure chamber, in particular in the form of an annular ring, which protrudes in the radial direction of the cooling valve beyond the axial valve opening. The pressure chamber can be filled with oil, in particular when the piston of the valve element closes the pressure chamber with respect to the axial bore on the radially inner side of the valve housing. The axial valve bore can here correspond to the relevant diameter of the valve element (or its piston) or have a slightly larger diameter than the valve element (or its piston), so that the valve element can be moved back and forth in the axial direction of the valve as friction-free and wear-free as possible within the axial valve bore. The valve chamber may also be connected to one or more ports of the valve, respectively. The valve chamber or chambers can be separated from one another or connected to one another by means of a piston valve element, in particular by means of a piston thereof.

The first embodiment enables an improved supply of the integrated actuating element by its three valve flanges with valve chambers and ports. In comparison with the system pressure valves known from the prior art for secondary system pressure circuits, the cooling priority valve according to the first embodiment of the invention has in particular an additional valve flange, by means of which the integrated starting element can be cooled preferentially. These three valve flanges with valve cavities and ports ensure that the total secondary flow is used for cooling the integrated starting element first. Only when the target amount of cooling oil for the integrated starting element is reached, a sufficient pressure is built up in the secondary circuit for displacing the valve element into the first control position and in particular opening the control edge of the valve element piston leading to the cooler. If the cooling of the integrated starting element is reduced after the starting process, more and more oil can flow to the cooler. Once the cooler is saturated, the valve element can be moved into a second control position and the control edge of the other piston of the valve element can be opened, so that the inlet is connected to the further outlet, in particular to the suction charging section, in order to convey excess oil in the direction of the suction charging section. The additional flange on the cooling priority valve is only slightly more expensive in terms of construction and also takes up little space. Furthermore, the additional valve flange can be realized at low cost. The efficiency of the hydraulic system may also be improved. For example, when 15 liters per minute of oil should be provided for cooling the integrated startup element, there is no need to provide additional oil volume flow for the cooler and suction plenum sections as required in the prior art.

In another embodiment, the piston rod of the valve cartridge includes one piston and another piston adjacent to the piston and disposed at an axial spacing. The valve chamber connected to the inlet in the initial position is separated by the piston and the further piston from the valve chamber connected to the outlet as well as from the valve chamber connected to the further outlet. In the first control position, the valve chamber connected to the inlet is connected to the valve chamber connected to the outlet and is separated from the valve chamber connected to the further outlet by the further piston. In the second control position, the valve chamber connected to the inlet is connected not only to the valve chamber connected to the outlet but also to the valve chamber connected to the further outlet.

Furthermore, the valve element can be pre-stressed into the initial position by the resetting element. The reset element may generate a pre-compression force. The valve element tends to remain in its initial position by a return force. As long as the pilot pressure is below the pre-compression force, the valve element can be held in its initial position, in particular, by the pre-compression force. For example, the reset element may act on a cup-shaped piston. The cup-shaped piston may form an interior space and an interior surface, such as a circular surface. The inner surface may extend perpendicular to the possible direction of movement of the spool. The return element may comprise, for example, a spring. The spring can be arranged, for example, in the interior of the cup-shaped piston and generate a restoring force in the form of a spring force which acts axially on the inner surface in the direction toward the outlet.

According to a second aspect of the present invention, a hydraulic system for a motor vehicle transmission is provided. The hydraulic system comprises the cooling priority valve, the secondary system pressure circuit, the cooler and the suction plenum section connected to the suction side of the pump of the hydraulic system according to the first aspect of the invention described above. The secondary system pressure circuit is connected to the inlet. Furthermore, according to a first alternative, the cooler can be connected with said outlet of the cooling priority valve and the suction plenum section can be connected with said further outlet of the cooling priority valve. According to a second alternative, the suction plenum section can be connected with the outlet and the cooler can be connected with the further outlet. Furthermore, the integrated starting element is connected to the secondary system pressure circuit bypassing the cooling priority valve. The term "bypass" is understood here to mean that the line section of the secondary system pressure circuit of the hydraulic system leads to the integrated starting element without the cooling priority valve being hydraulically connected in between.

The above-described embodiment provides the oil volume flow to the cooler, in particular when the cooling of the integrated starting element has been completely saturated. The lubrication section (which branches off in particular after the cooler) is thus also dependent on this. In order to provide minimal lubrication, in one embodiment, the hydraulic system comprises a bypass orifice, through which the secondary system pressure circuit is connected to the cooler and in particular also to a lubrication section located downstream of the cooler. The bypass orifice thus allows a certain amount of oil to be directed to the cooler and lubrication section and thereby prevents dry running of the transmission.

In combination with this, in one embodiment the cooler can be connected to the outlet and the suction plenum section to the further outlet, the bypass opening being connected on one side to an additional outlet which is connected to the valve chamber connected to the inlet. The bypass opening is connected on the other side to a line section which leads to the cooler, and an opening can also be provided upstream of the cooler.

In an alternative, the suction charging section is connected to the outlet and the cooler to the further outlet, and the bypass orifice is connected on one side to the secondary system pressure circuit and on the other side to the line section leading to the cooler, an orifice may also be provided upstream of the cooler.

With regard to the adjusting force or displacement force of the valve element relative to the valve housing, the valve element can be displaced in the valve body in the direction of the initial position by the pre-compression force of the return element and by the hydraulic pilot force. The hydraulic pilot force can be caused by the pressure prevailing in the first system pressure circuit of the hydraulic system, which acts on the same surface as the return element. In the opposite direction, the valve element is movable in the valve body in the direction of the first and second control positions by hydraulic pressure, which is caused by the pressure prevailing in the pressure circuit of the second system.

According to a third aspect of the invention, a motor vehicle transmission, in particular an automatic motor vehicle transmission, is provided. The motor vehicle transmission comprises a hydraulic system according to the second aspect of the invention.

According to a fourth aspect of the present invention there is provided a motor vehicle comprising a motor vehicle transmission according to the third aspect of the present invention.

Drawings

Embodiments of the invention are described in detail below with reference to the drawings, wherein like or similar elements have like reference numerals. The drawings are as follows:

FIG. 1 illustrates a vehicle including an engine and an automatic transmission having a hydraulic system;

FIG. 2 illustrates a hydraulic circuit diagram of a portion of a hydraulic system including a known secondary system pressure valve for the automatic transmission of FIG. 1;

FIG. 3 shows a first embodiment of a cooling priority valve according to the invention for the hydraulic system according to FIG. 2, wherein the cooling priority valve according to FIG. 3 can replace the secondary system pressure valve according to FIG. 2;

FIG. 4 shows a second embodiment of a cooling priority valve according to the invention for the hydraulic system according to FIG. 2, wherein the cooling priority valve according to FIG. 4 can replace the secondary system pressure valve according to FIG. 2;

FIG. 5 shows a third embodiment of a cooling priority valve according to the invention for the hydraulic system according to FIG. 2, wherein the cooling priority valve according to FIG. 5 can replace the secondary system pressure valve according to FIG. 2; and

Fig. 6 shows a fourth embodiment of a cooling priority valve according to the invention for the hydraulic system according to fig. 2, wherein the cooling priority valve according to fig. 6 can replace the secondary system pressure valve of fig. 2.

Detailed Description

Fig. 1 shows a motor vehicle 1, in the example shown a car (Pkw). The motor vehicle 1 comprises an internal combustion engine 2 which drives the motor vehicle 1 via a motor vehicle transmission in the form of an automatic transmission 3.

The automatic transmission includes a hydraulic system 4.

Fig. 2 shows a part of a circuit diagram of the hydraulic system 4 for an automatic transmission according to fig. 1. The hydraulic system 4 comprises a known secondary system pressure valve 5', which can be replaced by a cooling priority valve 5 according to the invention, for example shown enlarged in fig. 3, 4, 5 or 6. The structure of the cooling priority valve 5 is first described in detail below. The other elements of the hydraulic system 4 are described next. The way in which the cooling priority valve 5 and its surroundings function is described here above in connection with the hydraulic system 4.

Fig. 3 shows a cooling priority valve 5, which comprises a valve housing 6 and a valve spool 7. The spool 7 is reciprocable in the valve housing 6 along the longitudinal axis L of the cooling priority valve 6 in axial directions x1 (first direction) and x2 (second direction) opposite to each other. The valve element 7 is pretensioned by means of a return element in the form of a spring element 8 in the initial position shown in fig. 3. The spring element 8 is arranged in the region of the second end face S2 of the cooling priority valve 5.

In the region of the first end face S1 on the opposite side of the cooling priority valve 5, the cooling priority valve 5 has a first valve flange 9. The first valve flange 9 may be formed by the valve housing 6. The first valve flange 9 is configured hollow in the interior and forms a first valve chamber 10 which extends further outwards in the radial direction r of the cooling priority valve 5 than an axial bore 11 of the valve housing 6 which extends in the longitudinal direction L of the cooling priority valve 5. The valve housing 6 also has a first port 12 in the region of the first valve chamber 10, which can be connected to the first valve chamber. The first port 12 may in particular serve as an inlet for oil, so that the oil may fill the first valve chamber 10.

The cooling priority valve 5 has a second valve flange 13 adjacent to the first valve flange 9 and arranged axially spaced apart from the first valve flange 9 in the second direction x 2. The second valve flange 13 may be formed by the valve housing 6. The second valve flange 13 is configured hollow in the interior and forms a second valve chamber 14 which extends further outwards in the radial direction r of the cooling priority valve 5 than the axial bore 11 of the valve housing 6 which extends in the longitudinal direction L of the cooling priority valve 5. The valve housing 6 also has a second port 15 in the region of the second valve chamber 14, which can be connected to the second valve chamber 14. The second port 15 may in particular serve as an outlet for oil, so that oil may drain from the second valve chamber 14.

The cooling priority valve 5 has a third valve flange 16 adjacent to the second valve flange 13 and arranged axially spaced apart from the second valve flange 13 in the second direction x 2. The third valve flange 16 may be formed by the valve housing 6. The third valve flange 16 is configured hollow in the interior and forms a third valve chamber 17 which extends further outwards in the radial direction r of the cooling priority valve 5 than the axial bore 11 of the valve housing 6 which extends in the longitudinal direction L of the cooling priority valve 5. The valve housing 6 also has a third port 18 in the region of the third valve chamber 17, which can be connected to the third valve chamber 17. The third port 18 may in particular serve as an inlet for oil, so that the oil may fill the third valve chamber 17.

The cooling priority valve 5 has a fourth valve flange 19 adjacent to the third valve flange 16 and arranged axially spaced apart from the third valve flange 16 in the second direction x 2. The fourth valve flange 19 may be formed by the valve housing 6. The fourth valve flange 19 is configured hollow in the interior and forms a fourth valve chamber 20 which extends further outwards in the radial direction r of the cooling priority valve 5 than the axial bore 11 of the valve housing 6 which extends in the longitudinal direction L of the cooling priority valve 5. The valve housing 6 also has a fourth port 21 in the region of the fourth valve chamber 20, which can be connected to the fourth valve chamber 20. The fourth port 21 may in particular serve as an outlet for oil, so that oil may be discharged from the fourth valve chamber 20.

The cooling priority valve 5 has a fifth valve flange 22 adjacent to the fourth valve flange 19 and arranged axially spaced apart from the fourth valve flange 19 in the second direction x 2. The fifth valve flange 22 may be formed by the valve housing 6. The fifth valve flange 22 is configured hollow in the interior and forms a fifth valve chamber 23 which extends further outwards in the radial direction r of the cooling priority valve 5 than the axial bore 11 of the valve housing 6 which extends in the longitudinal direction L of the cooling priority valve 5. The valve housing 6 also has a fifth port 24 in the region of the fifth valve chamber 23, which can be connected to the fifth valve chamber 23. The fifth port 24 may in particular serve as an outlet for oil, so that oil may be discharged from the fifth valve chamber 23.

The cooling priority valve 5 has a sixth valve flange 25 adjacent to the fifth valve flange 22 and arranged axially spaced apart from the fifth valve flange 22 in the second direction x 2. The sixth valve flange 25 may be formed by the valve housing 6. The sixth valve flange 25 is configured hollow in the interior and forms a sixth valve chamber 26 which extends further outwards in the radial direction r of the cooling priority valve 5 than the axial bore 11 of the valve housing 6 which extends in the longitudinal direction L of the cooling priority valve 5. The valve housing 6 also has a sixth port 27 in the region of the sixth valve chamber 26, which can be connected to the sixth valve chamber 26. The sixth port 27 may in particular serve as an inlet for oil, so that the oil may fill the sixth valve chamber 26.

The spool 7 has a piston rod 28. A plurality of pistons 29, 30, 31 and 32 are provided on the piston rod 28. The respective pistons 29, 30, 31 and 32 are in this case in particular fixedly connected to the piston rod 28. The pistons 29, 30, 31 and 32 extend further to the outside than the piston rod 28 in the radial direction r of the spool 7. The diameters of the pistons 29, 30, 31 and 32 are selected such that they can reciprocate in the longitudinal direction L, in particular (highly) sealed, in the axial bore 11 of the valve housing 6. The valve chambers 10, 14, 17, 20, 23, and 26 in turn extend further outward in the radial direction r of the spool 7 than the pistons 29, 30, 31, and 32.

The first piston 29 is arranged here in the region of the first end face S1. Furthermore, a second piston 30 is arranged adjacent to the first piston 29 and axially spaced apart from the first piston 29 in the second direction x 2. The third piston 31 is in turn adjacent to the second piston 30 and is arranged axially spaced apart from the second piston 30 in the second direction x 2. Finally, in the region of the second end face S2, the fourth piston 32 is arranged adjacent to the third piston 31. The third piston 31 and the fourth piston 32 may be constructed in one piece or two pieces.

Regardless of the position of the spool 7 relative to the valve body 6 (i.e., the initial position, the first control position, and the second control position, as described below), the first piston 29 seals the first valve chamber 10 relative to the second valve chamber 14 so that there is no connection between the first valve chamber 10 and the second valve chamber 14. Whereby the first port 12 is also not connected to the second port 15.

Similarly, regardless of the switching position of the spool 7 relative to the valve body 6 (i.e., the initial position, the first control position, and the second control position described below), the fourth piston 32 seals the sixth valve chamber 26 relative to the fifth valve chamber 23, so that there is no connection between the sixth valve chamber 26 and the fifth valve chamber 23. Whereby the sixth port 27 is also not connected to the fifth port 24.

The fourth piston 32 is cup-shaped and forms an inner space 33 and an inner hydraulically effective surface 34, which extends in the radial direction r (and thus transversely to the longitudinal direction L). The spring element 8 generates a pre-compression force which acts on the inner hydraulically active surface 34 of the fourth piston 32 in the first direction x 1. The sixth valve chamber 26 is connected to the inner space 33 of the fourth piston 32.

In the initial position of the valve element 7 shown in fig. 3, the valve element 7 is preloaded by the spring element 8 in a first end position, in which the first piston 29 is located in the first valve chamber 10. In the initial position, the second piston 30 seals the third valve chamber 17 relative to the second valve chamber 14, so that the third valve chamber 17 is not connected to the second valve chamber 14. Whereby the third port 18 (inlet) is also not connected to the second port 15 (outlet).

In addition, in the initial position of the spool 7 shown in fig. 3, the third piston 31 covers the fourth valve chamber 20. The third piston 31 seals the fourth valve chamber 20 in this case, so that the fourth valve chamber 20 is not connected to the third valve chamber 17 nor to the fifth valve chamber 23. Whereby neither the fourth port 21 (the other outlet) is connected to the third port 18 (the inlet) nor the fifth port 24.

The valve spool 7 is movable in the second direction x2 such that the valve spool 7 moves out of the initial position according to fig. 3 and occupies the first control position. In the first control position the second piston 30 releases the connection between the second valve chamber 14 and the third valve chamber 17 via the control edge 35 of the second piston 30. Thereby, the third port 18 (inlet) is connected with the second port 15 (outlet).

The geometry of the valve element 7 is designed such that the third piston 31 still covers the fourth valve chamber 20 in the first control position of the valve element 7. The third piston 31 here continues to seal the fourth valve chamber 20, so that the fourth valve chamber 20 is not connected to the third valve chamber 17 nor to the fifth valve chamber 23. Whereby neither the fourth port 21 (the other outlet) is connected to the third port 18 (the inlet) nor the fifth port 24.

The valve spool 7 is further movable in the second direction x2 such that the valve spool 7 moves out of the first control position and occupies a second control position in which the third piston 31 no longer completely covers the fourth valve chamber 20. The third piston 31 thus releases the fourth valve chamber 20 via the control edge 36 of the third piston 31, so that the fourth valve chamber 20 is connected to the third valve chamber 17. Whereby the third port 18 (inlet) is now also connected to the fourth port 21 (further outlet).

In the second control position the second piston 30 also releases the connection between the second valve chamber 14 and the third valve chamber 17 via the control edge 35 of the second piston 30 and the third port 18 (inlet) remains connected to the second port 15 (outlet).

The valve element 7 is movable in the valve body 6 in the first axial direction x1 by the spring force of the spring element 8 and the hydraulic pilot force. The hydraulic pilot force is caused by the pressure prevailing in the main system pressure circuit 43 of the hydraulic system 4. In the opposite direction, the valve spool 7 is movable in the second axial direction x2 within the valve body 6 by hydraulic pressure caused by the pressure prevailing in the secondary system pressure circuit 39. The spring force, the pilot force and the pressure are explained in detail below.

The spool 7 forms a hydraulically effective end surface 37, such as a circular surface or an annular surface, on the first end surface S1. In the initial position of the valve element 7 according to fig. 3, the hydraulically effective end surface 37 is located in the first valve chamber 10. The first valve chamber 10 is connected through the first port 12 and through a first orifice 38 to a secondary system pressure circuit 39 of the hydraulic system 4.

Pressurized oil from the secondary system pressure circuit 39 may be supplied to the first valve chamber 10 via the first orifice 38 and the first port 12. The oil may fill the first valve chamber 10 and establish a first pressure within the first valve chamber 10. A first pressing force corresponding to this first pressure can act on the hydraulically effective end surface 37 of the first piston 29 in the second direction x2 within the first valve chamber 10 (thus against the spring force and the pilot force of the spring element 8).

Pressurized oil from the secondary system pressure circuit 39 may further be supplied via the third port 18 to the third valve chamber 17 and the axial bore 11 in the region between the third valve chamber 17 and the fourth valve chamber 20. The oil may fill the third valve chamber 17 and the axial bore 11 between the second piston 30 and the third piston 31 and establish a second pressure in both chambers. The second pressing force corresponding to the second pressing force can act on the end face 40 of the second piston 30 in the first axial direction x1 and on the end face 41 of the third piston 31 in the second axial manner x 2. Since the end face 40 of the second piston 30 has the same area value as the end face 41 of the third piston 31 in the example shown in fig. 3, the second pressure does not cause movement of the spool 7. The oil in the third valve chamber 17 is used for supply to the second valve chamber 14 (in the first and second control positions of the spool 7) and the fourth valve chamber 20 (in the second control position of the spool 7).

The sixth valve chamber 26 is connected via a sixth port 27 and a second orifice 42 to a main system pressure circuit 43 of the hydraulic system 4. Oil may be supplied to the sixth valve chamber 26 and the inner space 33 via the sixth port 27. The oil may fill the sixth valve chamber 26 and the interior space 33 and establish a pilot pressure within the interior space 33. The pilot pressure acts on the inner hydraulic active surface 34 of the fourth piston 32. The pilot pressure corresponding to the pilot pressure acts on the inner hydraulic pressure effective surface 34 of the fourth piston 32 in the first direction x1 and enhances the elastic force generated by the spring element 8.

In order to control the various pressures within the automatic transmission 3, the hydraulic system 4 according to fig. 2 includes the above-described primary system pressure circuit 43, secondary system pressure circuit 39, and return section 44. The three mentioned loops 39, 43 and 44 may be saturated according to priority.

The hydraulic system 4 may be supplied with hydraulic fluid, in particular oil, by a main pump in the form of a hydraulic pump 45 (see fig. 4). The hydraulic pump 45 may deliver an amount of oil that increases in proportion to the rotational speed of the hydraulic pump 45. The hydraulic pump 45 can in particular be driven by the internal combustion engine 2 (see fig. 1). In order to reduce the torque consumption of the hydraulic pump 45, a so-called "dual circuit pump" may be used, as shown in fig. 2, wherein the pressure in the flow of the two-stroke vane pump is reduced once the main system pressure circuit 43 is saturated (self-regulating system).

The main system pressure present in the main system pressure circuit 43 may be controlled by a main system pressure valve 46, which is supplied with oil by a hydraulic pump 45. The pressure in the main system pressure circuit 43 can be variably regulated here by a first pressure regulator 47. The main system pressure circuit 43 supplies pressurized oil to a clutch, not shown, of the automatic transmission 3 at a first priority to make the clutch on to transmit motor torque. When the primary system pressure circuit 43 is saturated, oil is supplied to the secondary system pressure circuit 39 (second priority). The secondary system pressure circuit 39 is divided into a section 48 for cooling and lubricating the transmission and a section 49 for cooling the starting element 50.

The pressure in the secondary system pressure circuit 39 may be, for example, one third of the pressure in the primary system pressure circuit 43. When the secondary system pressure circuit 39 is also saturated, the amount of oil that is excessively fed by the hydraulic pump 45 is led into the return section 44 (which may also be referred to as a suction plenum section), from where the oil is supplied to the pump suction side 51 (third priority). The secondary system pressure valve 5 'here has the task of a pressure reducing valve, through which the excess oil does not pass through the primary system pressure valve 46, but through the secondary system pressure valve 5' to the suction-charging section 44.

The second pressure regulator 52 controlling the integrated starting element 50 is supplied with pressurized oil by the main system pressure circuit 43. When the motor vehicle 1 is in operation, a large heat input of the integrated starting element 50 must be dissipated. The secondary system pressure circuit 39 thus uses a certain oil volume flow for cooling the integrated startup element 50. The oil quantity can be controlled here by means of a cooling valve 53.

As shown in fig. 2, the oil amount of the secondary system pressure circuit 39 is divided into a cooling oil flow to the integrated starter element 50 and a cooling oil flow through the cooler 54 of the automatic transmission 3. Downstream of the cooler 54, a lubrication section 59 of the secondary system pressure circuit 39 can also branch off. The lubrication section 59 directs the oil of the secondary system pressure circuit 39 to a lubrication point of the transmission 3. The split ratio of the cooling oil flow at maximum actuation of the cooling valve 53 is determined by the ratio of the third orifice 55 located upstream of the integrated startup element 50 and the fourth orifice 56 located upstream of the cooler 54.

In order to provide a specific cooling oil flow for the integrated startup element 50, a volume flow must also flow through the cooler 54 according to the split ratio. These two volumetric flows add up to the total secondary demand, which depends on the pressure in the secondary system pressure circuit 39, which in turn depends on the pressure in the main system pressure circuit 43. The oil quantity for the integrated starting element 50 can thus be reduced by the cooling valve 53 and the oil flow through the cooler 54 can thus be increased. But on the other hand it is not possible to reduce the oil flow through the cooler 54 (outside the split ratio) and increase the flow through the integrated starting element 50 by means of the hydraulic system 4 according to fig. 2.

In particular, the integrated starting element 50 must be cooled down intensively during starting. The output rotational speed in this transmission 3 is very low, so that no high cooler flow (or lubrication) is required. However, as described above, the cooler flow cannot be reduced (outside the split ratio) by the hydraulic system 4 without reducing the cooling of the integrated starting element 50. The secondary requirement affects the size (ccm/U) of the oil pump, as sufficient secondary oil must be provided to ensure the required cooling of the integrated starting element 50 in the case of starting. For example, orifice 55/orifice 56 split = 1.5. To provide 15 liters/minute for the integrated startup element 50, 10 liters/minute must flow through the cooler 54. The secondary requirement is therefore 25 liters/min.

In order to improve the cooling oil supply of the integrated starting element 50, the secondary system pressure valve 5' according to fig. 2 can be replaced in the hydraulic system 4 by a cooling priority valve 5 according to the invention, for example according to fig. 3,4, 5 or 6. The cooling priority valve 5 has an additional valve flange compared to the secondary system pressure valve 5'.

The integrated starting element 50 can be cooled preferentially on the cooling priority valve 5. When the spool 7 of the cooling priority valve 5 is in the initial position, the total amount of oil flowing through the secondary system pressure circuit 39 is first guided into the section 49 for cooling the integrated starting element (see, for example, fig. 3).

Only when the target oil quantity for cooling the integrated starting element 50 is reached is sufficient pressure built up in the secondary system pressure circuit 39 to move the valve element 7 into its first control position. In the first control position, the second piston 30 of the valve element 7 releases the connection between the second valve chamber 14 and the third valve chamber 17 of the cooling priority valve 5 via the control edge 35 of the second piston 30. Thereby, the third port 18 (inlet) is connected with the second port 15 (outlet). Since the third port 18 is connected with the secondary system pressure circuit 39, the secondary system pressure circuit 39 can supply oil to the section 48 leading to the cooler 54 in the first control position of the spool 7. When the target oil amount for cooling the integrated starting element 50 is, for example, 15 liters/min, it is only necessary to provide these 15 liters/min in the secondary system pressure circuit. No additional volumetric flow demand is created for the cooler 54.

If the cooling of the integrated starting element 50 decreases after the starting process, more and more oil flows to the cooler 54. Once the section 48 leading to the cooler 54 is saturated, the spool 7 of the cooling priority valve 5 is moved into its second control position. The third piston 31 of the cooling priority valve 5 in the second control position no longer completely covers the fourth valve chamber 20. The third piston 31 thereby releases the fourth valve chamber 20 via the control edge 36 of the third piston 31, so that the fourth valve chamber 20 is connected to the third valve chamber 17. So that now the third port 18 (inlet) is also connected to the fourth port 21 (further outlet). The secondary system pressure circuit 39 can thus supply oil to the suction plenum section 44 in the second control position of the spool 7.

Fig. 4 shows a further cooling priority valve 5, which differs from the cooling priority valve 5 according to fig. 3 in that: the section 48 leading to the cooler 54 is connected to the fourth port 21 (instead of being connected to the second port 15 as shown in fig. 3) and the suction plenum section 44 is connected to the second port 15 (instead of being connected to the fourth port 21 as shown in fig. 3). This can be achieved simply by varying the control time on the spool 7. This embodiment simplifies the installation of the cooling priority valve 5 in the hydraulic control.

Fig. 5 shows a further cooling priority valve 5, which differs from the cooling priority valve 5 according to fig. 3 in that: it additionally has a bypass orifice 57 which is connected on one side to the third valve chamber 17 via an additional port 58 on the third valve flange 16 of the valve housing 6. The valve chamber 17 is supplied with oil from the secondary system pressure circuit 39 through the third port 18. On the other side, the bypass orifice 57 is connected with the section 48 leading to the cooler 54 and the lubrication section 59 of the transmission 3. Thus, the bypass orifice 57 still allows minimal lubrication of the transmission when the spool 7 of the cooling priority valve 5 is in the initial position. An amount of oil (e.g. 3 litres/min) may be led to the cooler 54 and the lubrication section 59 and thus prevent dry running of the transmission 3. If the cooling of the integrated starting element 50 as shown in the above example requires 15 litres/min, the total demand is 18 litres/min, which still means a saving of 7 litres/min compared to the known hydraulic system according to fig. 2.

Fig. 6 shows a further cooling priority valve 5, which differs from the cooling priority valve 5 according to fig. 5 in that: the section 48 leading to the cooler 54 and lubrication section is connected to the fourth port 21 (instead of being connected to the second port 15 as shown in fig. 5), and the suction enhancement device 44 is connected to the second port 15 (instead of being connected to the fourth port 21 as shown in fig. 5). This can be achieved simply by varying the control time on the spool 7. This embodiment simplifies the installation of the cooling priority valve 5 in the hydraulic control. Furthermore, the bypass orifice 57 is connected on one side directly upstream of the third port 18 to the secondary system pressure circuit 39. On the other side, a bypass orifice 57 is connected with the section 48 leading to the cooler 54 and lubrication section of the transmission 3. Thus, the bypass orifice 57 also enables minimal lubrication of the transmission when the spool 7 of the cooling priority valve 5 is in the initial position.

List of reference numerals

B integrated starting element

Axial radial direction of L/r main system pressure valve

First/second end face of S1/S2 main system pressure valve

1. Motor vehicle

2. Internal combustion engine

3. Automatic transmission

4. Hydraulic system

5. Cooling priority valve

5' Secondary system pressure valve

6. Valve housing

7. Valve core

8. Spring element

9. First valve flange

10. First valve cavity

11. Axial bore in valve housing

12. First port of cooling priority valve

13. Second valve flange

14. Second valve cavity

15. Second port of cooling priority valve

16. Third valve flange

17. Third valve cavity

18. Third port of Cooling priority valve

19. Fourth valve flange

20. Fourth valve cavity

21. Fourth port of cooling priority valve

22. Fifth valve flange

23. Fifth valve cavity

24. Fifth port of cooling priority valve

25. Sixth valve flange

26. Sixth valve cavity

27. Sixth port of cooling priority valve

28. Piston rod

29. First piston

30. Second piston

31. Third piston

32. Fourth piston

33. Interior space

34. Hydraulically active surface

35. Control edge of second piston

36. Control edge of third piston

37. Hydraulic effective end face

38. A first orifice

39. Pressure loop of secondary system

40. End face of second piston

41. End face of third piston

42. A second orifice

43. Main system pressure loop

44 Return section/suction plenum section

45. Hydraulic pump

46. Main system pressure valve

47. First pressure regulator

48 For cooling and lubricating a section of a transmission

49 For cooling the section of the integrated starting element

50. Integrated starting element

51. Suction side of pump

52. Second pressure regulator

53. Cooling valve

54. Cooling device

55. Third orifice

56. Fourth orifice

57. Bypass orifice

Additional ports on third valve flange 58

Lubrication section of 59 secondary system pressure circuit

Claims

1. A hydraulic system (4) for a motor vehicle transmission, the hydraulic system (4) comprising a cooling priority valve (5), the cooling priority valve (5) comprising a valve housing (6), a valve spool (7), an inlet (18), one outlet (15) and a further outlet (21), wherein a secondary system pressure circuit (39) of the hydraulic system (4) is connectable to the inlet (18), a cooler (54) is connectable to the outlet (15) or to the further outlet (21), a suction plenum section (44) is connectable to the outlet (15) or to the further outlet (21), the cooling priority valve (5) being configured for moving the valve spool (7) within the valve housing (6) into an initial position in which the inlet (18) is neither connected to the outlet (15) nor to the further outlet (21), a first control position in which the inlet (18) is connectable to the outlet (15), and a second control position in which the inlet (18) is connected to the further outlet (21); the valve element (7) forms a hydraulic effective surface (37) at the position of the first end face of the valve element (7) and a hydraulic effective surface (34) at the position of the second end face of the valve element (7), which are arranged opposite to each other on the two end faces of the valve element (7), the valve element being movable in the valve housing in the direction of the initial position by means of a pre-compression force of a return element, which is caused by a pressure prevailing in a main system pressure circuit (43) of the hydraulic system, and by means of a hydraulic pilot force acting on the hydraulic effective surface (34) formed at the position of the second end face of the valve element (7), and in the opposite direction the valve element being movable in the valve housing in the direction of the first and second control positions by means of a hydraulic pressure, which is caused by a pressure prevailing in a secondary system pressure circuit (39), and which acts on the hydraulic effective surface (37) formed at the position of the first end face of the valve element (7);

The hydraulic system (4) further comprises: a secondary system pressure circuit (39); a cooler (54); a suction-pressurization section (44) connected to a suction side (51) of a pump (45) of the hydraulic system (4), wherein,

A secondary system pressure circuit (39) is connected to the inlet (18),

A cooler (54) is connected to the outlet (15) and a suction plenum section (44) is connected to the further outlet (21), or a suction plenum section (44) is connected to the outlet (15) and a cooler (54) is connected to the further outlet (21),

The integrated starting element (50) is connected to the secondary system pressure circuit (39) by bypassing the cooling priority valve (5),

A primary system pressure circuit (43) supplies pressurized oil to a clutch of the transmission at a first priority to turn the clutch on to transfer motor torque, and when the primary system pressure circuit (43) is saturated, oil is supplied to a secondary system pressure circuit (39), the secondary system pressure circuit (39) being divided into sections for cooling and lubricating the transmission and sections for cooling the integrated starting element.

2. The hydraulic system (4) according to claim 1, characterized in that,

The valve housing (6) has three valve flanges (13, 16, 19),

The three valve flanges (13, 16, 19) each form a valve chamber (14, 17, 20),

The inlet (18), the outlet (15) and the further outlet (21) are provided on one of the valve flanges (13, 16, 19), respectively, and

The inlet (18), the outlet (15) and the further outlet (21) are each connected to one of the valve chambers (14, 17, 20).

3. Hydraulic system (4) according to claim 1 or 2, characterized in that the piston rod (28) of the valve spool (7) comprises one piston (30) and another piston (31) adjacent to the piston (30) and arranged at an axial distance, wherein,

The valve chamber (17) connected to the inlet (18) in the initial position is separated by the piston (30) and the further piston (31) from the valve chamber (14) connected to the outlet (15) and also from the valve chamber (20) connected to the further outlet (21),

The valve chamber (17) connected to the inlet (18) is connected to the valve chamber (14) connected to the outlet (15) in a first control position and is separated from the valve chamber (20) connected to the further outlet (21) by the further piston (31),

In the second control position, the valve chamber (17) connected to the inlet (18) is connected to both the valve chamber (14) connected to the outlet (15) and also to the valve chamber (20) connected to the further outlet (21).

4. Hydraulic system (4) according to claim 1 or 2, characterized in that the valve spool (7) is pre-stressed in an initial position by a reset element (8).

5. The hydraulic system (4) according to claim 1, characterized in that the hydraulic system (4) further comprises a bypass orifice (57) through which the secondary system pressure circuit (39) is connected with the cooler (54).

6. The hydraulic system (4) according to claim 5, characterized in that,

A cooler (54) is connected to the outlet (15) and a suction plenum section (44) is connected to the further outlet (21),

The bypass orifice (57) is connected on one side to an additional outlet (58) which is connected to a valve chamber (17) connected to the inlet (18), and

The bypass opening (57) is connected on the other side to a line section (48) which leads to the cooler (54).

7. The hydraulic system (4) according to claim 5, characterized in that,

A suction plenum section (44) is connected to the outlet (15) and a cooler (54) is connected to the further outlet (21), and

The bypass orifice (57) is connected on one side to the secondary system pressure circuit (39) and

8. A motor vehicle transmission (3) comprising a hydraulic system (4) according to any one of claims 1 to 7.

9. Motor vehicle transmission (3) according to claim 8, characterized in that the motor vehicle transmission (3) is an automatic motor vehicle transmission.

10. A motor vehicle (1) comprising an automatic transmission of a motor vehicle according to claim 9.